Fix some long-standing type-hinting issues in SAPP models.

Summary:
# Problem

We have a lot of Pyre type-errors we've been suppressing since D22039123 landed back in 2020.

# Solution

The thing is, we don't have to live like this. We can just annotate these Column fields on Tables ourselves, with the correct type.

So let's do that, and let's.

Reviewed By: alexblanck, compositor

Differential Revision: D55171548

fbshipit-source-id: 56f6e2978102438de176de48ca05d8711bb1195d

sapp/db_support.py

@@ -301,17 +301,14 @@ class PrimaryKeyBase(PrepareMixin, RecordMixin):  # noqa
     __tablename__ = "primary_keys"
     __table_args__: Tuple[Dict[str, str]] = BASE_TABLE_ARGS
 
-    # pyre-fixme[8]: Attribute has type `str`; used as `Column[str]`.
-    table_name: str = Column(
+    table_name: Column[str] = Column(
         String(length=100),
         doc="Name of the table that this row stores the next available primary key for",
         nullable=False,
         primary_key=True,
     )
 
-    # pyre-fixme[8]: Attribute has type `int`; used as
-    #  `Column[Variable[sqlalchemy.sql.type_api._U]]`.
-    current_id: int = Column(
+    current_id: Column[int] = Column(
         BIGINT(unsigned=True).with_variant(BIGINT, "sqlite"),
         doc="The current/latest id used in the table.",
         nullable=False,